Multi-hazard assessment under climate change in the aerotropolis coastal city of Kulon Progo, Yogyakarta – Indonesia

Climate change is an issue that can affect the dynamics of coastal areas. Besides storing abundant potential resources, coastal areas also contain potential hazards related to climate change, including in Indonesian coastal areas. Aerotropolis coastal city of Kulon Progo is one of the areas in Indonesia with those potentials. The survival of the coastal region is essential to Kulon Progo’s vital operations as an aerotropolis city, starting with tourism, the economy, and investment. However, these activities lead to changes in coastal characteristics that climate change exacerbates. We can perform some steps to prevent and reduce coastal hazards, e.g., multi-hazard assessment. The coastal multi-hazards model comprised five types of hazards: ecosystem disruption, gradual inundation, seawater intrusion, erosion, and coastal flooding. The potential for coastal hazards may increase as coastal characteristics change. Therefore, this study aims to identify coastal characteristics based on biogeophysical parameters and to model the spatial distribution of coastal multi-hazards in the Kulon Progo using the Coastal Hazard Wheel (CHW) method. The analysis of biogeophysical parameters according to CHW shows that the coastal area of Kulon Progo consists of sedimentary plain and river mouth landforms. Wave exposure is moderately exposed, with significant wave heights ranging from 2.05 to 2.42 m. The tidal range is included in the class of meso tides with a value range of 2.09 to 2.34 m. The flora/fauna parameters consist of areas not covered by vegetation and covered by coastal forest ecosystem vegetation. Most sediment balances in coastal areas experience a deficit with an average erosion rate of 5.49 m/year. Still, some shorelines encounter a surplus with an average accretion rate of 3.96 m/year. Coastal areas of Kulon Progo are not affected by tropical cyclone activity. The multi-hazard model results indicate a moderate level of ecosystem disruption hazard; moderate to high gradual inundation hazard; moderate to high seawater intrusion hazard; low, high, and very high erosion hazard; and a moderate to very high coastal flooding hazard. The variation in the hazard level depends on the factors such as landform, wave exposure, tidal range, sediment balance, flora/fauna, and storm climate.